SWEET DAYS OF DISCIPLINE by Fleur Jaeggy, translated by Tim Parks. (New Directions: $9.95, paperback original; 112.) This, her fourth novel, is Jaeggy's American debut. The delicate precision and restraint of the writing makes an otherwise straightforward memory of boarding school in postwar Switzerland sweet and exotic. Like all boarding schools, the Bausler Institut in the Appenzell is a pressure cooker for girls from all over the world, trying to reign in their adolescent yearnings under strict German tutelage. But Frederique, the object of the author's 14-year-old affections "had something the others didn't have; all I could do was justify her talent as a gift passed on from the dead. You only had to hear her reciting the French poets in class to realize that they had come to her, were reincarnated in her." "A sort of chaste promiscuity" pervades the school, the memory of the school and the writing about the school. When a memory is so well-preserved, like those little solemn faces full of yearning; when its effect on the present is not fully fleshed out, nothing rivals its intensity. That is what Jaeggy does with this memory of her obsession with Frederique. She preserves its intensity forever.